Answer
$m^3+3m^2n+3mn^2+n^3$
Work Step by Step
Using the $n=
3
$ row of Pascal's Triangle as the coefficients and following the pattern in the expansion of a binomial, the expression $
(m+n)^3
$ expands to
\begin{array}{l}
m^3+3m^2n+3mn^2+n^3
.\end{array}